The overall goal of this research is to understand the molecular mechanisms that are responsible for the regulated expression of genetic information in higher organisms. We are studying two multi-gene families in the mouse: the genes specifying the light and heavy chain immunoglobulins and those coding for the ribosomal structural proteins. We are using recombinant DNA technology to isolate the genes and to purify sequences corresponding to their specific messenger RNAs. A battery of methods including restriction fragment analysis, DNA and RNA blotting techniques, nucleotide sequencing and kinetic analysis of radioactively labeled RNA will be used to study the organization of these genes and transcription, processing and turnover of their messenger RNA products. In the case of the immunoglobulin genes particular attention will be devoted to understanding the bases for gene rearrangements and the altered modes of expression which occur during B-cell ontogeny. Studies of the ribosomal protein genes will include attempts at chromosomal mapping and at elucidating the principles underlying their coordinate expression.